1. Field of the Invention
The present invention relates to a stereoscopic image pickup apparatus and method of adjusting an optical axis. More particularly, the present invention relates to a stereoscopic image pickup apparatus in which an optical difference between two image pickup units can be corrected rapidly and by a simple structure, and a method of adjusting an optical axis.
2. Description Related to the Prior Art
A stereoscopic camera is known as an image pickup apparatus for creating and recording image data of a stereoscopic image. For example, JP-A 2006-033346 discloses the stereoscopic camera including a plurality of image pickup units, each of which picks up an object image of an object focused by a lens system. Image data from the image pickup units is obtained for the single object, to create the stereoscopic image data.
It is important in the stereoscopic camera to suppress offsetting of images due to offsetting of optical axes of the two image pickup units. JP-A 2003-052058 discloses a method of correcting offsetting of the optical axes. An shift amount of the optical axes is detected from two images obtained by the two image pickup units, to adjust an area of an image for being cropped after image pickup and a position of an image pickup device according to the shift amount.
JP-A 8-317424 discloses a method in which the shift amount of the optical axes are stored in association with focal lengths of the two lens systems, and the offsetting of the optical axes due to movement of a variator lens is corrected by changing an area to be read of an image according to the focal lengths or the position of the variator lens. U.S. Pat. No. 7,102,686 (corresponding to JP-A 11-355624) discloses the stereoscopic camera in which a first one of the image pickup units is kept slidable and rotatable from a second one of the image pickup units, so as to change an interval of the image pickup units, an angle of the optical axis and the like automatically.
However, the method of JP-A 2003-052058 and JP-A 8-317424 has a problem in that processing for changing the area to be read of an image requires considerably long time. The shift amount of the optical axes may not be corrected only by adjusting the area to be read of the image. If a position of an image pickup device requires adjusting, a problem arises in that the stereoscopic camera is likely to have an excessively large size. Also, the structure of U.S. Pat. No. 7,102,686 (corresponding to JP-A 11-355624) has a problem of an excessively large size because of sliding and rotating of the first one of the image pickup units relative to the second.